Prosthetic Heart Valve Configured to Receive a Percutaneous Prosthetic Heart Valve Implantation

ABSTRACT

The invention is a prosthetic heart valve, and associated methods therefore, configured to replace a native heart valve, and having a support frame configured to be reshaped into an expanded form in order to receive and/or support an expandable prosthetic heart valve therein. The prosthetic heart valve may be configured to have a generally rigid and/or expansion-resistant configuration when initially implanted to replace a native valve (or other prosthetic heart valve), but to assume a generally non-rigid and/or expanded/expandable form when subjected to an outward force such as that provided by a dilation balloon.

FIELD OF THE INVENTION

The present invention relates to a prosthetic heart valve for heartvalve replacement, and more particularly to a prosthetic heart valveconfigured to receive an expandable prosthetic heart valve therein.

BACKGROUND OF THE INVENTION

In humans and other vertebrate animals, the heart is a hollow muscularorgan having four pumping chambers separated by four heart valves:aortic, mitral (or bicuspid), tricuspid, and pulmonary. The valves openand close in response to a pressure gradient during each cardiac cycleof relaxation and contraction to control the flow of blood to aparticular region of the heart and/or to blood vessels (pulmonary,aorta, etc.)

These valves are comprised of a dense fibrous ring known as the annulus,and leaflets or cusps attached to the annulus. For some valves, there isalso a complex of chordae tendinae and papillary muscles securing theleaflets. The size of the leaflets or cusps is such that when the heartcontracts the resulting increased blood pressure formed within heartchamber forces the leaflets open to allow flow from the heart chamber.As the pressure in the heart chamber subsides, the pressure in thesubsequent chamber or blood vessel becomes dominant, and presses backagainst the leaflets. As a result, the leaflets or cusps come inapposition to each other, thereby closing the passage.

Heart valve disease is a widespread condition in which one or more ofthe valves of the heart fails to function properly. Diseased heartvalves may be categorized as either stenotic, wherein the valve does notopen sufficiently to allow adequate forward flow of blood through thevalve, and/or incompetent, wherein the valve does not close completely,causing excessive backward flow of blood through the valve when thevalve is closed. Valve disease can be severely debilitating and evenfatal if left untreated. Various surgical techniques may be used toreplace or repair a diseased or damaged valve. In a traditional valvereplacement operation, the damaged leaflets are typically excised andthe annulus sculpted to receive a replacement prosthetic valve.

In many patients who suffer from dysfunction of the mitral and/ortricuspid valves(s) of the heart, surgical repair of the valve (i.e.,“valvuloplasty”) is a desirable alternative to valve replacement. Forsome patients, however, the condition of the native heart valve requirescomplete replacement using a prosthetic heart valve. Prosthetic heartvalves have been known for some time, and have been successfullyimplanted using traditional open-chest surgical approaches,minimally-invasive procedures, and so-called percutaneous methods.

A prosthetic heart valve typically comprises a support structure (suchas a ring and/or stent) with a valve assembly deployed therein. Thesupport structure is often rigid, and can be formed of variousbiocompatible materials, including metals, plastics, ceramics, etc. Twoprimary types of “conventional” heart valve replacements or prosthesesare known. One is a mechanical-type heart valve that uses a ball andcage arrangement or a pivoting mechanical closure supported by a basestructure to provide unidirectional blood flow, such as shown in U.S.Pat. No. 6,143,025 to Stobie, et al. and U.S. Pat. No. 6,719,790 toBrendzel, et al., the entire disclosures of which are hereby expresslyincorporated by reference. The other is a tissue-type or “bioprosthetic”valve having flexible leaflets supported by a base structure andprojecting into the flow stream that function much like those of anatural human heart valve and imitate their natural flexing action tocoapt against each other and ensure one-way blood flow.

In tissue-type valves, a whole xenograft valve (e.g., porcine) or aplurality of xenograft leaflets (e.g., bovine pericardium) can providefluid occluding surfaces. Synthetic leaflets have been proposed, andthus the term “flexible leaflet valve” refers to both natural andartificial “tissue-type” valves. In a typical tissue-type valve, two ormore flexible leaflets are mounted within a peripheral support structurethat usually includes posts or commissures extending in the outflowdirection to mimic natural fibrous commissures in the native annulus.Components of the valve are usually assembled with one or morebiocompatible fabric (e.g., Dacron) coverings, and a fabric-coveredsewing ring is provided on the inflow end of the peripheral supportstructure.

In many bioprosthetic-type valves, a metallic or polymeric structureprovides base support for the flexible leaflets, which extend therefrom.One such support is a “support frame,” sometimes called a “wireform” or“stent,” which has a plurality (typically three) of large radius cuspssupporting the cusp region of the flexible leaflets (i.e., either awhole xenograft valve or three separate leaflets). The ends of each pairof adjacent cusps converge somewhat asymptotically to form upstandingcommissures that terminate in tips, each extending in the oppositedirection as the arcuate cusps and having a relatively smaller radius.The support frame typically describes a conical tube with the commissuretips at the small diameter end. This provides an undulating referenceshape to which a fixed edge of each leaflet attaches (via componentssuch as fabric and sutures) much like the natural fibrous skeleton inthe aortic annulus. One example of the construction of a flexibleleaflet valve is seen in U.S. Pat. No. 6,585,766 to Huynh, et al.(issued Jul. 1, 2003), in which the exploded view of FIG. 1 illustratesa fabric-covered wireform 54 and a fabric-covered support stent 56 oneither side of a leaflet subassembly 52. The contents of U.S. Pat. No.6,585,766 are hereby incorporated by reference in their entirety. Otherexamples of valve and related assemblies/systems are found in U.S. Pat.No. 7,137,184, which issued on Nov. 21, 2006, the contents of which arehereby incorporated by reference in their entirety.

Sometimes the need for complete valve replacement may arise after apatient has already had an earlier valve replacement for the same valve.For example, a prosthetic heart that was successfully implanted toreplace a native valve may itself suffer damage and/or wear and tearmany years after initially being implanted.

Implanting a prosthetic heart valve into a patient with apreviously-implanted prosthetic heart valve typically involvesadditional steps from a similar procedure in a patient with nopreviously-implanted heart valve. Implanting the prosthetic heart valvedirectly within a previously-implanted prosthetic heart valve isgenerally impractical, in part because the new prosthetic heart valve(including the support structure and valve assembly) will have to residewithin the annulus of the previously-implanted heart valve, andtraditional prosthetic heart valves are not configured to easily receivesuch a valve-within-a-valve implantation in a manner which providessecure seating for the new valve while also having a large enoughannulus within the new valve to support proper blood flow therethrough.Implanting a prosthetic heart valve in a patient who previously had aprosthetic heart valve generally requires the previously-implanted heartvalve to be removed during the same procedure in which the newprosthetic heart valve is implanted. In such cases, a surgeon can use atraditional surgical approach to install the prosthetic valve, which caninvolve the surgeon cutting out the previously-implanted heart valvefrom the heart valve annulus, and then implanting the new prostheticvalve into the heart valve annulus.

Percutaneous and minimally-invasive heart valve replacement has beendeveloped recently, wherein a prosthetic heart valve is advancedpercutaneously (e.g., via the femoral artery or other desiredapproaches) or via other approaches (i.e., minimally-invasive “keyhole”surgery, including approaches via the apex of the heart, etc.) into theheart valve annulus, and then expanded within the heart valve annulus.Various expandable valves are being tested, primarily that use balloon-or self-expanding stents as anchors. For the purpose of inclusivity, theentire field will be denoted herein as the delivery and implantation ofexpandable valves, regardless of whether the delivery method involvespercutaneous, minimally-invasive, or other delivery methods. Thesevalves typically include a scaffold or frame that expands radiallyoutward into direct anchoring contact with the annulus, sometimesassisted with barbs. Examples of percutaneous heart valves and deliverysystems and methods therefore are described in U.S. Pat. No. 5,411,552,issued May 2, 1995; U.S. Pat. No. 5,840,081, issued Nov. 24, 1998; U.S.Pat. No. 6,168,614, issued Jan. 2, 2001; and U.S. Pat. No. 6,582,462,issued Jun. 24, 2003; and also in U.S. patent application Ser. No.11/280,062, filed Nov. 16, 2005; U.S. patent application Ser. No.11/488,510, filed Jul. 18, 2006; and U.S. patent application Ser. No.11/542,087, filed Oct. 2, 2006; the contents of each of which are herebyincorporated by reference in their entirety.

Percutaneous heart valve replacement is often performed without cuttingout the native heart valve, wherein the prosthetic heart valve isexpanded in the native heart valve annulus and the native valve leafletsare pressed against the valve annulus walls by the expanded prostheticheart valve. However, in cases where a previously-implanted prostheticheart valve is present, deploying a prosthetic heart valve within thenative heart valve may be impractical. The shape and structure of thepreviously-installed prosthetic heart valve may interfere with theproper placement, deployment, and functioning of the new prostheticheart valve.

There is thus a need for a prosthetic heart valve which will properlyreplace a damaged heart valve, but will also enable a replacementexpandable prosthetic heart valve to be deployed therein at a latertime. The current invention meets this need.

SUMMARY OF THE INVENTION

The invention is a prosthetic heart valve configured to receive aprosthetic heart valve, such as a catheter-deployed (transcatheter)prosthetic heart valve, therein. In one embodiment, the prosthetic heartvalve has a support structure which is generally resistant to expansionwhen deployed in the patient's native heart valve annulus to replace thenative heart valve (or to replace another prosthetic heart valve), butis configured to transform to a generally expanded and/or expandableconfiguration in order to receive a prosthetic heart valve therein. Thetransformation from expansion-resistant to expanded/expandable can beachieved by subjecting the expansion-resistant support structure to anoutward force, such as a dilation force, which may be provided by adilation balloon used to deploy a replacement prosthetic valve.

The prosthetic heart valve structure may be generally rigid prior todilation, and may be configured to become generally non-rigid, and evengenerally elastic, when subjected to an outward force. The elasticitymay assist in holding a percutaneously-introduced prosthetic valvewithin the current prosthetic valve structure.

The prosthetic valve can be initially deployed in the patient's valveannulus using various surgical techniques (e.g., traditional open-chest,minimally-invasive, percutaneous, etc.) to correct heart valve function.If the heart valve function declines further after deployment of theprosthetic valve, a new replacement prosthetic valve can be deployedwithin the previously-deployed prosthetic valve without the need toexcise the previously-deployed prosthetic valve. Deployment of thereplacement prosthetic valve within the previously-deployed prostheticvalve can occur at a much later time from initial deployment of thepreviously-deployed prosthetic valve. The prosthetic valve of thecurrent invention is configured to be deployed in a patient and, at alater time, to accept and even improve deployment of a replacementprosthetic valve within the same valve annulus.

In one embodiment, the structure can include a core comprising a spring,a plastically deformable material (including breakable materials), etc.The core may be formed as a single piece (possibly with one or moreweakened sections configured to fail when subjected to a sufficientforce), or may be formed from several segments connected at seams. Thecore may form an inner lumen through which further attachment devicesmay be passed, such as elastic and/or inelastic cords.

A prosthetic valve according to an embodiment of the invention mayinclude a cover configured to hold the core together after it has beendilated. For example, where a core breaks into multiple pieces duringdilation, the cover can serve to keep the pieces from separating fromthe prosthetic valve. The cover can also serve to hold the core and/orother portions of the support frame in a desired shape, and may haveelastic properties.

In an embodiment of the invention, the prosthetic valve is a stentedbioprosthetic valve configured to expand and contract dynamically withinthe patient's annulus. The dynamic motion of the annulus can enable thevalve opening to expand during periods of peak demand, and reduce theannular restriction to the increased flow. The expansion can alsodecrease leaflet stresses associated with potential higher gradients.The expansion can also permit later placement of an expandableprosthetic valve within the stented bioprosthetic valve.

In an embodiment of the invention, a prosthetic valve has a supportstructure having a generally rigid and/or expansion-resistant portionincluding a core. The prosthetic valve may include plasticallydeformable materials configured to maintain the prosthetic valve supportstructure in the generally rigid and/or expansion-resistant shape fordeployment. The plastically deformable materials may be configured tobreak or otherwise plastically deform and no longer maintain the supportstructure in the generally rigid and/or expansion-resistantconfiguration when subjected to a dilation force. The support structuremay form a continuous loop, and may include elastically deformablematerial configured to provide tension about the continuous loop afterthe support structure has been dilated by a dilation balloon.

A method for repairing a patient's heart function according to anembodiment of the invention can include: providing a prosthetic heartvalve configured to have a generally rigid and/or expansion-resistantsupport structure upon implantation and also configured to assume agenerally non-rigid and/or expanded/expandable configuration upondilation; and implanting the prosthetic heart valve in a heart valveannulus. The method may also include deploying an expandable prostheticheart valve within the previously-deployed heart valve and heart valveannulus. Deploying the expandable prosthetic heart valve within thepreviously-deployed prosthetic valve and heart valve annulus may includedilating the previously-deployed prosthetic valve to cause thepreviously-deployed prosthetic valve to assume a generally non-rigidand/or expanded/expandable shape.

Dilating a previously-deployed prosthetic heart valve may include usinga dilation balloon, such as the type currently used for dilation ofnative heart valves, which can be advanced within thepreviously-deployed prosthetic heart valve and expanded to a desiredpressure and/or diameter. As a general rule, dilation balloons used fordilation of native valves are formed from generally inelastic materialto provide a generally fixed (i.e., pre-set) outer diameter wheninflated. Once such balloons are inflated to their full fixed diameter,they will not appreciably expand further (prior to rupturing) even ifadditional volume/pressure is added therein. Typical pressures forinflating such balloons are between 1 and 6 atmospheres, with pre-setinflated outer diameters of such balloons being on the order of 18 to 33millimeters. The dilation balloon may be expanded to a desired pressure(e.g., 1-6 atmospheres) sufficient to fully inflate the dilation balloonto its desired diameter and to dilate and expand the previously-deployedprosthetic heart valve.

A typical surgically-implanted prosthetic heart valve will withstanddilation pressures of several atmospheres such as provided by mostdilation balloons without expanding and/or becoming elastic. Bycontrast, the prosthetic heart valve of the current invention isconfigured to become expanded and/or generally elastic when subjected tosufficient pressure provided by a dilation balloon. If the dilationballoon is expanded, using sufficient pressure, to an expanded outerdiameter larger than the inner diameter of the prosthetic heart valve ofthe invention, the prosthetic heart valve will expand in diameter and/orbecome elastic.

In one embodiment, the dilation balloon is configured with a pre-setinflated outer diameter which is larger, such as by 10-20% or more, thanthe inner diameter of the previously-deployed prosthetic heart valve. Asan example, if the previously-deployed prosthetic heart valve of theinvention has an inner diameter of 23 mm, a dilation balloon having aninflated diameter of 24-27 mm may be inflated within the prostheticheart valve to cause it to expand and/or become elastic.

Prosthetic heart valves according to various embodiments of theinvention can be configured to be generally rigid prior to dilation, butbecome expanded and/or elastic when subjected to a sufficient dilationpressure. For example, a prosthetic heart valve could be configured towithstand naturally occurring dilation pressures that may occur duringbeating of the heart, but to become expanded and/or elastic whensubjected to a desired pressure (e.g., from a dilation balloon), such asa pressure of 1 atmosphere, 2 atmospheres, 3 atmospheres, 4 atmospheres,5 atmospheres, or 6 atmospheres, depending on the particularapplication.

Note that the dilation balloon inflated diameters and inflatedpressures, as well as the pressures at which the prosthetic heart valveof the invention would become expanded and/or elastic, set forth aboveare by way of example, and that the use of balloons with other pressuresand diameters, and of prosthetic heart valves configured to change shapeand/or expand and/or become elastic when subjected to other pressuresand expanded balloon diameters, are also within the scope of theinvention.

An annuloplasty ring is being developed having a structure that canexpand and/or otherwise change configuration in order to accept apercutaneously-delivered prosthetic heart valve therein. Such anannuloplasty ring is disclosed in U.S. patent application Ser. No.______ filed concurrently herewith and entitled “Annuloplasty RingConfigured to Receive a Percutaneous Prosthetic Heart ValveImplantation,” the entire contents of which are incorporated herein byreference.

Other features and advantages of the present invention will becomeapparent from the following detailed description, taken in conjunctionwith the accompanying drawings which illustrate, by way of example, theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a prosthetic heart valve deployed in a heart according toan embodiment of the invention;

FIGS. 2A-2C depict perspective, top, and side views, respectively, of aprosthetic heart valve according to an embodiment of the invention;

FIG. 2D depicts a top view of the prosthetic heart valve of FIGS. 2A-2Cafter the prosthetic heart valve has been dilated;

FIGS. 3A-3C depict side, top (in cross section), and close-up sectionalviews, respectively, of a prosthetic heart valve support structureaccording to an embodiment of the invention;

FIG. 3D depicts a top view of the prosthetic heart valve supportstructure of FIGS. 3A-3C after the prosthetic heart valve supportstructure has been dilated;

FIGS. 4A-4B depict top views of a prosthetic heart valve supportstructure in pre-dilation and post-dilation configurations,respectively, according to an embodiment of the invention;

FIGS. 5A-5B depict top views of a prosthetic heart valve supportstructure in pre-dilation and post-dilation configurations,respectively, according to an embodiment of the invention;

FIGS. 6A-6C depict top, side, and close-up sectional views,respectively, of a prosthetic heart valve support structure according toan embodiment of the invention;

FIG. 6D depicts a top view of the prosthetic heart valve supportstructure of FIGS. 6A-6C after the prosthetic heart valve supportstructure has been dilated;

FIGS. 6E and 6F depict close-up top views of a portion, in expanded andunexpanded configurations, respectively, of a prosthetic heart valvesupport structure according to an embodiment of the invention;

FIGS. 7A and 7B depict top views of unexpanded and expandedconfigurations, respectively, of a prosthetic heart valve supportstructure according to an embodiment of the invention;

FIG. 8A depicts an expandable prosthetic heart valve deployment catheterconfigured for annuloplasty ring dilation and expandable prostheticheart valve deployment according to an embodiment of the invention;

FIG. 8B depicts the expandable prosthetic heart valve deploymentcatheter of FIG. 8A positioned within a previously-deployed prostheticheart valve in a heart valve annulus of a patient according to anembodiment of the invention;

FIG. 8C depicts the expandable prosthetic heart valve deploymentcatheter of FIG. 8A dilating the previously-deployed prosthetic heartvalve and deploying an expandable prosthetic heart valve therewithinaccording to an embodiment of the invention;

FIG. 8D depicts the expandable prosthetic heart valve deploymentcatheter of FIG. 8A being withdrawn from the patient according to anembodiment of the invention;

FIG. 9A depicts an expandable prosthetic heart valve deployment catheterconfigured for dilation of a previously-deployed prosthetic heart valveand for deployment of an expandable prosthetic heart valve according toan embodiment of the invention;

FIG. 9B depicts the expandable prosthetic heart valve deploymentcatheter of FIG. 9A with the dilation balloon positioned within thepreviously-deployed prosthetic heart valve in the heart valve annulusaccording to an embodiment of the invention;

FIG. 9C depicts the expandable prosthetic heart valve deploymentcatheter of FIG. 9A dilating the previously-deployed prosthetic heartvalve according to an embodiment of the invention; and

FIG. 9D depicts the expandable prosthetic heart valve deploymentcatheter of FIG. 9A with the dilation balloon deflated after dilation ofthe previously-deployed prosthetic heart valve according to anembodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to FIG. 1, a prosthetic heart valve 10 according to theinvention is depicted in a heart 12. The heart 12 has four chambers,known as the right atrium 14, right ventricle 16, left atrium 18, andleft ventricle 20. The general anatomy of the heart 12, which isdepicted as viewed from the front of a patient, will be described forbackground purposes. The heart 12 has a muscular outer wall 22, with aninteratrial septum 24 dividing the right atrium 14 and left atrium 18,and a muscular interventricular septum 26 dividing the right ventricle16 and left ventricle 20. At the bottom end of the heart 12 is the apex28.

Blood flows through the superior vena cava 30 and the inferior vena cava32 into the right atrium 14 of the heart 12. The tricuspid valve 34,which has three leaflets 36, controls blood flow between the rightatrium 14 and the right ventricle 16. The tricuspid valve 34 is closedwhen blood is pumped out from the right ventricle 16 through thepulmonary valve 38 to the pulmonary artery 40 which branches intoarteries leading to the lungs (not shown). Thereafter, the tricuspidvalve 34 is opened to refill the right ventricle 16 with blood from theright atrium 14. Lower portions and free edges 42 of leaflets 36 of thetricuspid valve 34 are connected via tricuspid chordae tendinae 44 topapillary muscles 46 in the right ventricle 16 for controlling themovements of the tricuspid valve 34.

After exiting the lungs, the newly-oxygenated blood flows through thepulmonary veins 48 and enters the left atrium 18 of the heart 12. Themitral valve in a normal heart controls blood flow between the leftatrium 18 and the left ventricle 20. Note that in the current figure,the native mitral valve has been replaced with the prosthetic heartvalve 10, which is accordingly a prosthetic mitral valve 50. Theprosthetic mitral valve 50 is closed during ventricular systole whenblood is ejected from the left ventricle 20 into the aorta 52.Thereafter, the prosthetic mitral valve 50 is opened to refill the leftventricle 20 with blood from the left atrium 18. Blood from the leftventricle 20 is pumped by power created from the musculature of theheart wall 22 and the muscular interventricular septum 26 through theaortic valve 62 into the aorta 52 which branches into arteries leadingto all parts of the body.

In the particular embodiment depicted, the prosthetic heart valve 10 isdeployed to replace a native mitral valve, and more particularly issecured (via, e.g., sutures) adjacent and around the mitral valveannulus 64. Depending on the particular application, including themethod by which the prosthetic heart valve 10 was implanted, theparticular native valve (mitral, tricuspid, etc.) and/or some or all ofits associated structures may be entirely or partially removed prior toor during implantation of the prosthetic heart valve 10, or the nativevalve and/or some or all associated structures may simply be left inplace with the prosthetic heart valve 10 installed over the nativevalve. For example, a native mitral valve typically has two leaflets(anterior leaflet and posterior leaflet), lower portions and free edgesof which are connected via mitral chordae tendinae to papillary muscles60 in the left ventricle 20 for controlling the movements of the mitralvalve. Not all of these structures (i.e., mitral valve leaflets, chordaetendinae) are depicted in FIG. 1 because, in the particular embodiment,the native mitral valve and many associated structures (chordae, etc.)have been removed prior to or during implantation of the prostheticheart valve 10. However, in many prosthetic valve implantations,surgeons choose to preserve many of the chordae tendinae, etc., evenwhen excising the native valve.

Although FIG. 1 depicts a prosthetic mitral valve, note that theinvention can be applied to prosthetic valves (and systems and methodstherefore) configured to replacement of any heart valves, includingaortic, mitral, tricuspid, and pulmonary valves.

FIGS. 2A-2C depict a prosthetic heart valve 70 according to anembodiment of the invention, where the prosthetic heart valve 70comprises a support frame 72 and valve structure 74. In the particularembodiment depicted, the valve structure 74 comprises three heart valveleaflets 76. The prosthetic heart valve 70 has an inner diameter 78 a ofa valve orifice 80 through which blood may flow in one direction, butthe valve leaflets 76 will prevent blood flow in the opposite direction.The support frame 74 is generally rigid and/or expansion-resistant inorder to maintain the particular shape (which in this embodiment isgenerally round) and diameter 78 a of the valve orifice 80 and also tomaintain the respective valve leaflets 76 in proper alignment in orderfor the valve structure 74 to properly close and open. The particularsupport frame 74 also includes commissure supports 75. In the particularembodiment depicted in FIGS. 2A-2C, the support frame 74 defines agenerally rigid and/or expansion-resistant ring 82 which encircles thevalve 70 and defines a generally round valve orifice 80, but othershapes are also within the scope of the invention, depending on theparticular application (including issues such as the particular nativevalve to be replaced, etc.) The particular prosthetic heart valve 70includes visualization markers 73 (such as radiopaque markers, etc.),which in the current embodiment are on the support frame 74 andcorrespond to the ring 82 and also to the commissure supports 75 (andhence to the commissures), which can aid in proper placement of asubsequently-deployed expandable prosthetic heart valve within the valveorifice 80 of the prosthetic heart valve 70.

When the prosthetic heart valve 70 of FIGS. 2A-2C is subjected to adilation force (such as that from a dilation balloon, which may providepressures of 1 to 5 atmospheres), the prosthetic heart valve will beexpanded somewhat. The support frame 74 will transition from thegenerally rigid and/or expansion-resistant configuration of FIGS. 2A-2Cto a generally non-rigid and expanded configuration depicted in FIG. 2D.Note that the ring 82, which was generally rigid and/orexpansion-resistant, is now generally non-rigid and is expanded, and thevalve orifice 80 has accordingly been enlarged to a larger innerdiameter 78 b. The larger inner diameter 78 b is configured to receivean expandable prosthetic heart valve therein. The overall result is thatthe “post-dilation” prosthetic heart valve 70 of FIG. 2D has a generallylarger inner diameter circular opening 78 b. The actual inner diameterswill depend on the particular application, including aspects of theparticular patient's heart (e.g., native valve and/or annulus diameter,etc.). As an example, the pre-dilation inner diameter 78 a for a mitralvalve may be between 25-33 mm, or for an aortic valve 18-28 mm. Thepost-dilation inner diameter 78 b will be larger, and more specificallylarge enough to accommodate the outer diameter of an expandableprosthetic valve therein.

In some procedures where an expandable prosthetic heart valve is used toreplace/repair a previously-deployed prosthetic heart valve, it may bedesirable for the expandable prosthetic heart valve to have a deployed(expanded) inner diameter (and corresponding expandable prosthetic heartvalve orifice area) approximately equal to the pre-dilation innerdiameter 78 a (and corresponding pre-dilation prosthetic valve orificearea) of the previously-deployed prosthetic heart valve 70. Suchconsistency between inner diameters/orifice areas can be useful inmaintaining proper blood flow, so that the expandable prosthetic heartvalve will provide the same blood flow as was provided by thepreviously-deployed prosthetic heart valve. Note that the term “valveorifice area” refers to the area of the valve orifice when the valveportion is in the fully open configuration (e.g., with the valveleaflets in their fully open configuration so that the effective orificearea is at its maximum size).

For example, Edwards Lifesciences has Sapien™ expandable prostheticheart valves having outer diameters of 23 and 26 mm, respectively, whichhave corresponding inner diameters of about 20 and 23 mm, respectively.Accordingly, the post-dilation inner diameter 78 b of the(previously-deployed) prosthetic heart valve may be on the order of 23and 26 mm (respectively) to accommodate such expandable prosthetic heartvalves. This corresponds to a post-dilation inner diameter 78 b beingabout 10 to 20% larger than the pre-dilation inner diameter 78 a.Accordingly, embodiments of the invention include a prosthetic heartvalve having a post-dilation inner diameter 78 b that is about 10, 15,or 20%, or between 5-25%, 10-20%, or 13-17% of the pre-dilation innerdiameter 78 a.

Note that the invention is not limited to the above differences betweenpre- and post-dilation inner diameters. For example, there may beapplications where much smaller and/or much larger post-dilation innerdiameters may be required. In some cases an expandable prosthetic heartvalve will have an outer diameter only slightly larger than its innerdiameter, so that less expansion of the previously-deployed prostheticheart valve inner diameter is required in order to accommodate theexpandable prosthetic heart valve. In other cases an expandableprosthetic heart valve may have an outer diameter that is much largerthan its inner diameter, so that a greater expansion of thepreviously-deployed prosthetic heart valve inner diameter is necessaryto accommodate the expandable prosthetic heart valve. There may also beapplications where it may be desirable to deploy an expandableprosthetic heart valve having a smaller or larger inner diameter thanwas provided by the (previously-deployed and pre-dilation) prostheticheart valve.

Note that, depending on the particular embodiment, a prosthetic heartvalve 70 according to the invention may return to its pre-dilation innerdiameter 78 a after being subject to dilation such as from a balloondilation catheter. However, the balloon dilation will have rendered the“post-dilation” prosthetic heart valve 70 into a generally non-rigidand/or expansion-friendly configuration, so that the “post-dilation”prosthetic heart valve 70 will be forced with relative ease into alarger diameter (such as 78 b) when an expandable (e.g.,balloon-expandable, self-expanding, etc.) prosthetic heart valve isdeployed within the valve orifice 80 of the prosthetic heart valve 70.

FIGS. 3A-3C depicts a prosthetic heart valve 90 having a valve structure92 and support frame 94 according to a further embodiment of theinvention, with the prosthetic heart valve 90 having a valve orifice 96having an inner diameter 98 a. The support frame 94 has a generallyrigid and expansion-resistant core 100 formed from a single core element102 which is bent or otherwise formed into a generally circular shapewith opposing ends 104 a, 104 b meeting at a seam 106 so as to form thecomplete circle. The seam 106 may include adhesive, solder, welds, etc.in order to secure the two ends 104 a, 104 b together. The prostheticheart valve 90 includes a covering 108 around the support core 96. Thecovering 108 may be a cloth-like material, and may be a sewing ringconfigured to be sewn to the native heart valve annulus duringdeployment of the prosthetic heart valve 90. The covering 108 isgenerally flexible, and may be generally elastic. The covering 108 (or aportion thereof) may also be generally compressible, especially in theportion facing inward toward the valve orifice 96, which can assist inseating an expandable valve therein. A compressible material may beapplied onto or within the covering 108 in a position to provide acompressible region on the surface facing inward toward the valveorifice 96.

When the prosthetic heart valve 90 is subject to a dilation force suchas that from a dilation balloon catheter, the support frame 94 willbecome non-rigid and expanded. More particularly, the seam 106 of thecore 100 will rupture, so that the opposing ends 104 a, 104 b will beseparated by an opening 110, and the core 100 will assume a generallyC-shaped configuration as depicted in FIG. 3D. The covering 108 willstretch or otherwise expand circumferentially to accommodate theenlarged/expanded core 100, and the prosthetic heart valve 90 will havean enlarged inner diameter 98 b for the valve orifice 96. Depending onthe particular embodiment, including the particular construction of thecore 100 and/or covering, the (post-dilation) prosthetic heart valve 90may provide an inward (i.e., compressive) force toward the valve orifice96. For example, the core 100 may be formed of a generally resilientspring-like material and/or memory material, and may be biased somewhattoward its non-dilated configuration (i.e., with the opposing ends 104a, 104 b touching each other as in FIGS. 3A-3C). The covering 108 mayalso (or alternatively) be elastic and, after dilation of the prostheticheart valve 90, may provide an inward pull on the core 100 so as to biasthe opposing ends 104 a, 104 b toward each other. This inward pressurecan help to seat an expandable heart valve that may be deployed withinthe prosthetic heart valve 90. In an embodiment where compressiblematerial is provided (e.g., as part of the covering 108) facing inwardtoward the valve orifice 96, then the compressible material can provideadditional assistance in seating an expandable heart valve within theprosthetic heart valve 90.

FIG. 4A depicts a further embodiment of a support frame 120 for use witha prosthetic heart valve according to the invention. The support frame120 is generally circular and defines an inner diameter 122 a, and has agenerally rigid core 124 formed from a single core element 126 which isbent or otherwise formed into a generally circular shape with opposingends 128 a, 128 b which meet and connect at an overlapping section 130having a length 132 a. The overlapping section 130 may include adhesive,solder, welds, mechanical connections, etc. in order to secure theoverlapping ends 128 a, 128 b together. In the particular embodimentdepicted, the overlapping section 130 has a ratchet-like assembly formedfrom interacting portions 134 a, 134 b at or adjacent the opposing ends128 a, 128 b. The support frame 120 may include a covering (not shown)around the core 124.

FIG. 4B depicts the support frame 120 of FIG. 4A after it has beensubjected to a dilation force. The support frame 120 has been expandedto a larger inner diameter 122 b, with the core 124 enlarged so that theoverlapping section 130 is smaller, having a new shorter length 132 b.The dilation force caused the interacting portions 134 a, 134 b totemporarily release their connection to permit the relative movement ofthe overlapping ends 128 a, 128 b, but with the dilation force removedthe interacting portions 134 a, 134 b once again form a connection, sothat the support frame 120 is again generally rigid. Note that,depending on the particular application, a support frame could be formedsimilar to that of FIGS. 4A-4B but with the interacting portionsconfigured so that no fixed connection is formed between the overlappingends after dilation, so that the support frame will be generallynon-rigid after the dilation force has been applied. In such anembodiment, the support frame may be configured to provide (afterdilation) an inward (compressive) force upon any expandable prostheticvalve that may be deployed within the valve orifice of the original (andnow dilated) prosthetic valve. This inward compressive force may help toseat and otherwise hold the expandable prosthetic valve in its desiredposition within the native valve annulus and also within the now-dilated(prior) prosthetic valve.

FIGS. 5A-5B depict a further embodiment of a support frame 120 for usewith a prosthetic heart valve according to the invention. The supportframe 120 is similar to that depicted in FIG. 4A, except the overlappingsection 130 includes a sliding mechanical connection 136 having a slot137 secured to one opposing end 128 a, the second opposing end 128 bhaving been passed through the slot 137 to form the overlapping section130, and also including a spring 138 extending from the slot 137 to thesecond opposing end 128 b. The spring 138 permits expansion and/orcontraction of the support frame 120, with the spring 138 generallybiasing the support frame 120 toward a smaller diameter, such as thesmaller inner diameter 122 a of FIG. 5A, but also permitting the supportframe 120 to be expanded, when subject to an outside force such as adilation balloon and/or expandable prosthetic valve, to a largerdiameter such as the inner diameter 122 b of FIG. 5B. Note that thespring 138 can also permit the support frame 120 (and associated valveannulus) to move with physiological annular dynamic motion, e.g., tomake smaller expansions and/or contractions in response to normal valvefunction/heart movement as the patient's heart beats and pumps bloodthrough the valve. The support frame 120 may include a covering (notshown) around the core 124. The support frame 120 may be formed ofvarious materials, including elgiloy. The spring 138 can be configuredto provide a specific force in opposing expansion of the support frame120, and may be configured so that the force provided is insufficient tooppose the dilation force from a dilation balloon and/or expandablestent which might be expanded within the support frame 120. The spring138 could be formed from traditional coil springs, compressiblematerials, pleated sewing rings, accordion sewing rings, and otherconfigurations configured to provide a spring-like force.

In another embodiment of the invention, a prosthetic heart valveincludes a support frame having a rigid and/or expansion-resistant coreconfigured to separate into a plurality of pieces when subjected to adilation force. Such a rigid and/or expansion-resistant core could beformed as a single piece, which might include one or more weak pointsthat are subject to separation when subjected to a dilation force. Inone embodiment a rigid and/or expansion-resistant core could be formedfrom a plurality of segments positioned in edge-to-edge fashion andconfigured to separate when subjected to a dilation force. FIGS. 6A-6Cdepict one such embodiment of a support frame 140 for use with aprosthetic heart valve according to the invention. The support frame 140is generally circular (although other shapes are within the scope of theinvention) and defines an orifice 141 having an inner diameter 142 a,and has a generally rigid and/or expansion-resistant core 144 formedfrom multiple core segments 146 which are arranged in edge-to-edgefashion to form the generally circular shape of the core 144. Eachsegment 146 has an inner lumen 148, with the segments 146 when assembledinto the core 144 forming a continuous core lumen 150.

Adjacent segments 146 join at seams 152, which may include adhesive,solder, welds, etc. in order to secure and/or seal the seam 152 betweenthe adjacent segments 146. The support frame 140 has a pre-dilation cord154 and a post-dilation cord 156 passing through the core lumen 150. Thepre-dilation cord 154 may be a generally inelastic cord which issufficiently tight to hold adjacent segments together and to preventunwanted dilation of the support frame 140. A covering (not shown) mayalso be included to cover the core 144. The covering may be formed ofcloth, and may be elastic.

Both the seams 152 and pre-dilation cord 154 are configured to fail orstretch when subjected to a dilation force, such as that provided by adilation balloon, whereupon the support frame 140 will assume theexpanded configuration depicted in FIG. 6D, with an enlarged innerdiameter 142 b. For example, the pre-dilation cord 154 may be aninelastic cord configured to fail when subject to a selected force, suchas 1, 2, 3, 4, or more atmospheres, which are within the range of forcesprovided by many dilation balloons used in percutaneously-deployed heartvalve procedures. In one embodiment, the seams 152 are merely sealed,with the sealant providing little if any securement against separationof adjacent segments 146. In such an embodiment, the pre-dilation cord154 may serve as the sole device to hold the core segments 146 togetherin the rigid and/or expansion-resistant (pre-dilation) configuration.Once the pre-dilation cord 154 fails or stretches due to the dilationpressure, essentially all of the seams 152 will separate so thatadjacent segments 146 separate with spaces 158 separating the adjacentsegments 146. The remaining portions of the pre-dilation cord 154 remainwithin the support frame 140 after dilation.

The post-dilation cord 156 remains intact after dilation and may serveto hold the support frame 140 together post-dilation. The post-dilationcord 156 could be elastic, and/or could be inelastic and have a largerdiameter, and possibly a higher failure strength, than the pre-dilationcord 154. If the post-dilation cord 156 is elastic, it may provide aninward compressive force into the central orifice 141. If thepost-dilation cord 156 is generally inelastic, it will remain intactafter dilation either because its strength was too great to be rupturedby the dilation balloon or because it had a diameter that was largerthan that of the inflated dilation balloon.

In a variation of the embodiment of FIGS. 6A-6D, the pre-dilation cord154 could be left out of the support frame 140, and the seams 152themselves could have adhesive or other connections that serve to holdthe segments 146 together prior to dilation. In a further variation, thepre-dilation cord 154 could be left out of the support frame, with apost-dilation cord 156 configured to be elastic and with sufficientstrength/elasticity to provide an inward compressive force into thecentral orifice with sufficient strength to hold the segments 146together prior to dilation, but with the inward compressive force weakenough to permit the support frame 140 to be dilated and to permit anexpandable prosthetic heart valve to be deployed therein. Accordingly,the post-dilation cord 156 would serve as both pre-dilation cord andpost-dilation cord.

Visualization references (such as the visualization markers 73 fromFIGS. 2A-2D) may be included on or in various portions of the device.For example, visualization references may be placed on, in, or adjacentthe support frame 140, core 144, segments 146, pre-dilation cord 154,and/or post-dilation cord 156, etc. in the device of FIGS. 6A-6D. Suchvisualization references can help a user to properly position a dilationballoon and/or subsequently-deployed expandable prosthetic heart valvewithin the previously-deployed prosthetic heart valve having the supportframe 140. For example, visualization markers positioned at thegenerally rigid support frame 140 (or more specifically at the segments146 and/or the pre-dilation cord 154 and/or post-dilation cord 156)could be used to guide delivery and expansion of a dilation balloon, andalso to confirm that the support frame 140 has been dilated. Thevisualization markers could also be used to guide delivery and expansionof the expandable prosthetic heart valve within the support frame 140,and to confirm proper deployment of the expandable prosthetic heartvalve.

The support frame 140 may have segments 146 having ends 146 a, 146 bwhich interlock and/or otherwise interact in order to hold the segments146 together and/or in alignment. As depicted in the close-up view ofFIG. 6E, adjacent segments 146 may include interconnecting ends 146 a,146 b, with one end 146 a having a member 147 configured to be receivedwithin the lumen 148 or other opening in an end 146 b of an adjacentsegment 146. The interconnecting ends 146 a, 146 b keep the adjacentsegments 146 in a desired alignment so that the segment ends 146 a, 146b cannot slide sideways with respect to the member 147 and lumen 148,but does permit the segments 146 to be pulled apart, as depicted in FIG.6F, in order to permit expansion of the support frame 140 (as wasdepicted in FIG. 6D). The pulling apart of the segments 146 may beopposed by various structures set forth herein which oppose and/orrestrict dilation of a support frame, such as one or more elastic and/orinelastic cords 155 configured to oppose and/or restrict dilation of thesupport frame as was depicted in FIGS. 6A-6D.

FIGS. 7A-7B depict a further embodiment of the invention, with aprosthetic heart valve 160 having a valve structure 162 formed fromthree (3) leaflets 164 spaced around the valve orifice 166. The supportframe 168 includes a core 170 formed from three (3) segments 172. At thebase/perimeter of the valve structure 162, the edges 165 of each leaflet164 coincide with the edges of each respective segment 172 as well asthe seams 174 (and the commissure supports, if present). Adjacentsegments 172 are connected to each other at the seams 174, such as withadhesive(s), weld(s), etc., in order to form the rigid and/orexpansion-resistant (pre-dilation) support frame 168. Adjacent segments172 are also connected via individual inelastic cords 176 and elasticcords 178 extending between the adjacent segments 172. As depicted inFIG. 7A, the (pre-dilation) prosthetic valve 160 has a valve orifice 166having an inner diameter 180 a. A cloth cover (not shown) or similarcovering will also typically be included to cover the support frame 168and its associated elements (e.g., inelastic cords 176 and elastic cords178).

When the prosthetic heart valve 160 of FIG. 7A is subjected to adilation force, the seams 174 between the segments 172 will fail and thesupport frame 168 will separate into the three segments 172, as depictedin FIG. 7B. Note that in this particular embodiment the inelastic cords176 do not serve to hold adjacent segments against each other, butinstead permit adjacent segments to separate when subjected to adilation force. The inelastic cords 176 prevent excessive separationbetween any adjacent segments 172 as the dilation balloon (or otherdilation force) is applied, with the result being that the segments 172will all be spaced generally equally apart from each other once the fulldilation force is applied. After the dilation force is removed, theelastic cords 178 will serve to pull the adjacent segments toward eachother and to provide a generally inward (compressive) pressure to thevalve orifice 166 but while also maintaining the post-dilation innerdiameter 180 b (FIG. 7B) at a larger size than the pre-dilation diameter180 a (FIG. 7A). Because the leaflets 164 were positioned with theirbase edges coinciding with the seams 174 between segments 172, theleaflets 164 can remain generally intact after dilation and still permitthe segments 172 to separate to form the enlarged inner diameter 180 b.Note, however, that deploying a new expandable prosthetic valve withinthe prosthetic heart valve 160 will generally involve deploying anexpandable heart valve support stent that will crush the leaflets 164 ofthe current prosthetic heart valve 160 against the support frame 168,walls of the native valve annulus, and/or lumen.

If the prosthetic heart valve 160 includes commissure supports (notshown) on the support frame 168, the commissure supports can bepositioned on or adjacent the seams 174 between segments 172, and thecommissure supports can also be configured to split lengthwise when theprosthetic heart valve 160 is dilated so that one-half of eachcommissure support will remain with the adjacent segment 172 on eitherside of said commissure support. In such an embodiment, the edges of thevalve leaflets 164 can be secured (e.g., during assembly of theprosthetic heart valve 160) to the respective half of each commissuresupport, so that when the prosthetic heart valve 160 is dilated adjacentleaflets 164 can separate from adjacent leaflets 164, but each leaflet164 will still remain secured via its edges to its respective commissuresupport halves.

There are many variations of the above-cited embodiments, includingvarious combinations of the various embodiments. For example, thepre-dilation cord 154 and/or post-dilation cord 156 of FIGS. 6A-6D couldbe used with the core 100 of FIGS. 3A-3D in order to provide inwardcompressive force after the core 100 was dilated. The post-dilation cord156 of FIGS. 6A-6D could be replaced by a cover 108 such as thatdepicted in FIGS. 3A-3D, with the cover 108 serving to hold thepost-dilation core assembly (including any segments and/or piecesthereof) together and also (if formed form elastic material) providingan inward compressive force to the valve orifice.

FIG. 8A depicts an expandable prosthetic heart valve deployment catheter220 configured for (prior) prosthetic heart valve dilation and(replacement) expandable prosthetic heart valve deployment. Thedeployment catheter 220 has an elongated main body 222, a proximal end224, and a distal end 226. The proximal end 224 includes a handle 228.The distal end 226 includes a dilation balloon 230 upon which anexpandable prosthetic valve 232 is mounted. In the particular embodimentdepicted, the expandable prosthetic valve 232 includes a stent 234. Thedistal end 226 may also include one or more radiopaque markers 233 orsimilar visibility markers to improve visibility of the device withinthe patient when using fluoroscopy or other viewing technologies.

FIGS. 8B-8D depict deployment of an expandable prosthetic heart valve232 within a heart valve annulus 236 where a prosthetic heart valve 10has previously been deployed. The previously-deployed prosthetic heartvalve 10 may have been deployed using any methods, including methodscurrently known in the art such as traditional (open chest) surgery,minimally-invasive (e.g., keyhole) surgery, and percutaneous surgery.Depending on the particular application, the previously-deployedprosthetic heart valve 10 can be deployed in the patient years prior to,days prior to, hours prior to, or immediately prior to deployment of theexpandable prosthetic heart valve 232 as depicted in FIGS. 8B-8D.

FIG. 8B depicts the expandable prosthetic heart valve deploymentcatheter 220 of FIG. 8A with the distal end 226 advanced so that thedilation balloon 230 and expandable prosthetic heart valve 232 arepositioned within the previously-deployed prosthetic heart valve 10 inthe patient's heart 240. The previously-deployed prosthetic heart valve10 is seen in cross-section to show the generally rigid and/orexpansion-resistant support frame 238.

In the particular embodiment depicted in FIG. 8B, the deploymentcatheter 220 has been advanced over a guide wire 242, which was advancedinto the patient's heart 240 and previously-deployed prosthetic heartvalve 10 prior to advancement of the deployment catheter 220 into thepatient. Note that the use of a guide wire 242 is optional. Other guidedevices could also be used, in addition to or in lieu of a guide wire.For example, a guide catheter could be used, wherein a guide catheter isadvanced to a desired position within a patient, and the deploymentcatheter is then advanced into the patient inside of the guide catheteruntil the distal end of the deployment catheter extends from a distalopening in the guide catheter. A deployment catheter could also be usedwithout any sort of guide wire or guide catheter, so that the deploymentcatheter is guided by itself into the desired treatment location.

As depicted in FIG. 8C, once the dilation balloon 230 and expandableprosthetic heart valve 232 are properly positioned within the heartvalve annulus 234 and previously-deployed prosthetic heart valve 10, thedilation balloon 230 is expanded. The expanding dilation balloon 230forces the stent 234 to expand outwardly, and crushes the leaflets 244of the previously-deployed prosthetic heart valve 10 against the heartvalve annulus 236. The force from the expanding dilation balloon 230also dilates the previously-deployed prosthetic heart valve 10 and heartvalve annulus 236, forcing the support frame 238 of thepreviously-deployed prosthetic heart valve 10 to expand and/or becomenon-rigid.

In FIG. 8D, the dilation balloon 230 is deflated or otherwise reduced indiameter, with the new expandable prosthetic valve 232 deployed in theheart valve annulus 236 and previously-deployed prosthetic heart valve10, and also held in place by the stent 234. The outward pressure fromthe expanded stent 232, along with the inward pressure from the heartvalve annulus 236 and from any elastic portions (such as core, cords,and/or or covers) of the previously-deployed prosthetic heart valve 10or from the now-crushed previously-deployed prosthetic heart valveleaflets 244, combine to firmly seat the new expandable prosthetic valve232 in the desired position in the heart valve annulus 236 andpreviously-deployed prosthetic heart valve 10. The deployment catheter220 with the dilation balloon 230 can then be withdrawn from the heart240, leaving the new expandable prosthetic heart valve 232 in itsdeployed position within the patient and the previously-deployedprosthetic heart valve 10.

In a further embodiment of the invention, the previously-deployedprosthetic heart valve 10 is dilated in a separate step from deploymentof the expandable prosthetic heart valve 232. FIG. 9A depicts anexpandable prosthetic heart valve deployment catheter 220 configured forpreviously-deployed prosthetic heart valve dilation and expandableprosthetic heart valve deployment using two separate balloons, and morespecifically a distal balloon 230 a and a proximal balloon 230 b. Thedistal balloon 230 a is configured to deploy the new expandableprosthetic valve 232, which is positioned on the distal balloon 230 a,whereas the proximal balloon 230 b is configured for dilation of thepreviously-deployed prosthetic heart valve 10.

FIGS. 9B-9D depict dilation of the previously-deployed prosthetic heartvalve 10 and valve annulus 236 using the proximal balloon 230 b. In FIG.9B, the deployment catheter 220 has been advanced into the heart 230with the distal balloon 230 a (with expandable prosthetic valve 232thereon) advanced past the previously-deployed prosthetic heart valve10, and the proximal balloon 230 b positioned within thepreviously-deployed prosthetic heart valve 10 and valve annulus 236.

The proximal balloon 230 b is inflated or otherwise expanded, asdepicted in FIG. 9C, thereby dilating the previously-deployed prostheticheart valve 10 and valve annulus 236. The support frame 238 of thepreviously-deployed prosthetic heart valve 10 is expanded and/or assumesa generally non-rigid configuration, similarly to the changes previouslydiscussed with respect to the dilation discussed in FIG. 8C above.

After dilation of the previously-deployed prosthetic heart valve 10, theproximal balloon 230 b is deflated or otherwise reduced in diameter, asdepicted in FIG. 9D. The deployment catheter 220 may then be withdrawnfrom the patient until the proximal balloon 230 b is proximal of thepreviously-deployed prosthetic heart valve 10 and the distal balloon 230a is positioned within the previously-deployed prosthetic heart valve10. The distal balloon 230 a will be positioned within thepreviously-deployed prosthetic heart valve 10 in a similar fashion tothat depicted for balloon 230 in FIG. 8B. The distal balloon 230 a willthen be expanded to deploy the expandable prosthetic valve 232 inessentially the same manner as was discussed and depicted in FIGS.8B-8D. The distal balloon 230 a will serve to deploy the new expandableprosthetic valve 232, and may also serve to further dilate thepreviously-deployed prosthetic heart valve 10 and/or native valveannulus 236.

Note that the expandable prosthetic valve may be self-expanding, inwhich case the deployment catheter may not have a dilation balloon asdepicted in FIGS. 8A-8D and 9A-9D. Moreover, such a self-expandingprosthetic heart valve could be deployed with or without prior dilationof the previously-deployed prosthetic heart valve. For example, aself-expanding prosthetic heart valve may provide sufficient outwardradial force to dilate the previously-deployed prosthetic heart valveand/or to hold a now-dilated previously-deployed prosthetic heart valvein an expanded configuration in order to provide sufficient room for theself-expanding prosthetic heart valve in its expanded configuration.

While the invention has been described with reference to particularembodiments, it will be understood that various changes and additionalvariations may be made and equivalents may be substituted for elementsthereof without departing from the scope of the invention or theinventive concept thereof. In addition, many modifications may be madeto adapt a particular situation or device to the teachings of theinvention without departing from the essential scope thereof. Therefore,it is intended that the invention not be limited to the particularembodiments disclosed herein, but that the invention will include allembodiments falling within the scope of the appended claims.

1. A prosthetic heart valve comprising: a generally rigid structurehaving a circumference and configured to become non-rigid when subjectedto a dilation force; and a valve portion.
 2. The prosthetic heart valveof claim 1, wherein the generally rigid structure comprises a memberhaving opposing portions secured together via a connection, wherein theconnection is configured to fail when the prosthetic heart valve issubjected to a dilation force.
 3. The prosthetic heart valve of claim 1,wherein the generally rigid structure is configured to break into two ormore sections when subjected to a dilation force.
 5. The prostheticheart valve of claim 1, wherein the generally rigid structure comprisesa plurality of segments passing about the circumference.
 6. Theprosthetic heart valve of claim 5, further comprising: a generallyelastic member configured to pull at least two adjacent segments towardeach other.
 7. The prosthetic heart valve of claim 6, wherein thegenerally elastic member comprises a covering around the generally rigidstructure.
 8. The prosthetic heart valve of claim 6, wherein theplurality of segments form a lumen passing around the circumference, andthe generally elastic member passes through the lumen and around thecircumference.
 9. The prosthetic heart valve of claim 5, whereinadjacent segments are secured together at a seam configured to fail whenthe prosthetic heart valve is subject to a dilation force.
 10. Aprosthetic heart valve comprising: a generally rigid structure having acircumference and configured to become non-rigid and expand whensubjected to a dilation force; and a valve portion; wherein theprosthetic heart valve comprises a valve orifice having a valve orificearea, and the prosthetic heart valve is configured for the valve orificearea to be enlarged when the prosthetic heart valve is subjected to adilation force.
 11. The prosthetic heart valve of claim 10, wherein theprosthetic heart valve is configured for the valve orifice area to beenlarged by more than 10% when the prosthetic heart valve is subjectedto a dilation force.
 12. The prosthetic heart valve of claim 10, whereinthe prosthetic heart valve is configured for the valve orifice area tobe enlarged by more than 20% when the prosthetic heart valve issubjected to a dilation force.
 13. The prosthetic heart valve of claim10, wherein the valve orifice is generally circular prior to dilation.14. A method of repairing a patient's heart function, comprising:providing a first prosthetic heart valve having a generally rigidconfiguration, wherein the first prosthetic heart valve is configured toassume a generally non-rigid configuration when subjected to a dilationforce; and implanting the first prosthetic heart valve in a heart valveannulus.
 15. The method of claim 14, further comprising: providing asecond prosthetic heart valve, wherein the second prosthetic heart valveis radially expandable; and deploying a second prosthetic heart valvewithin the first prosthetic heart valve.
 16. The method of claim 15,wherein deploying the second prosthetic heart valve within the firstprosthetic heart valve further comprises: dilating the first prostheticheart valve to cause the first prosthetic heart valve to assume agenerally non-rigid configuration.
 17. The method of claim 16, whereinthe first prosthetic heart valve comprises a plurality of adjacentsegments secured at seams, and dilating the first prosthetic heart valvecomprises separating adjacent segments at the seams.
 18. The method ofclaim 17, wherein dilating the first prosthetic heart valve comprises:advancing a balloon catheter within the first prosthetic heart valve;and inflating the balloon catheter to a pressure of 4 atmospheres orless.
 19. The method of claim 18, wherein dilating the first prostheticheart valve comprises: inflating the balloon catheter to a pressure of 1atmosphere or less.
 20. The method of claim 18, wherein dilating thefirst prosthetic heart valve comprises: inflating the balloon catheterto a pressure of 1 atmosphere or less.